This invention relates to newly identified polynucleotides, polypeptides encoded by such polynucleotides, the use of such polynucleotides and polypeptides, as well as the production of such polynucleotides and polypeptides. More particularly, the polypeptide of the present invention have been putatively identified as fibroblast growth factor/heparin binding growth factor, hereinafter referred to as “FGF-14”. The invention also relates to inhibiting the action of such polypeptides.
Fibroblast growth factors are a family of proteins characteristic of binding to heparin and are, therefore, also called heparin binding growth factors (HBGF). Expression of different members of these proteins are found in various tissues and are under particular temporal and spatial control. These proteins are potent mitogens for a variety of cells of mesodermal, ectodermal, and endodermal origin, including fibroblasts, corneal and vascular endothelial cells, granulocytes, adrenal cortical cells, chondrocytes, myoblasts, vascular smooth muscle cells, lens epithelial cells, melanocytes, keratinocytes, oligodendrocytes, astrocytes, osteoblasts, and hematopoietic cells.
Each member has functions overlapping with others and also has its unique spectrum of functions. In addition to the ability to stimulate proliferation of vascular endothelial cells, both FGF-1 and 2 are chemotactic for endothelial cells and FGF-2 has been shown to enable endothelial cells to penetrate the basement membrane. Consistent with these properties, both FGF-1 and 2 have the capacity to stimulate angiogenesis. Another important feature of these growth factors is their ability to promote wound healing. Many other members of the FGF family share similar activities with FGF-1 and 2 such as promoting angiogenesis and wound healing. Several members of the FGF family have been shown to induce mesoderm formation and to modulate differentiation of neuronal cells, adipocytes and skeletal muscle cells.
Other than these biological activities in normal tissues, FGF proteins have been implicated in promoting tumorigenesis in carcinomas and sarcomas by promoting tumor vascularization and as transforming proteins when their expression is deregulated.
The FGF family presently consists of eight structurally-related polypeptides: basic FGF, acidic FGF, int 2, hst 1/k-FGF, FGF-5, FGF-6, keratinocyte growth factor, AIGF (FGF-8) and recently a glia-activating factor has been shown to be a novel heparin-binding growth factor which was purified from the culture supernatant of a human glioma cell line (Miyamoto, M. et al., Mol. and Cell. Biol., 13(7):4251-4259 (1993). The genes for each have been cloned and sequenced. Two of the members, FGF-1 and FGF-2, have been characterized under many names, but most often as acidic and basic fibroblast growth factor, respectively. The normal gene products influence the general proliferation capacity of the majority of mesoderm and neuroectoderm-derived cells. They are capable of inducing angiogenesis in vivo and may play important roles in early development (Burgess, W. H. and Maciag, T., Annu. Rev. Biochem., 58:575-606, (1989)).
Many of the above-identified members of the FGF family also bind to the same receptors and elicit a second message through binding to these receptors.
A eukaryotic expression vector encoding a secreted form of FGF-1 has been introduced by gene transfer into porcine arteries. This model defines gene function in the arterial wall in vivo. FGF-1 expression induced intimal thickening in porcine arteries 21 days after gene transfer (Nabel, E.G., et al., Nature, 362:844-6 (1993)). It has further been demonstrated that basic fibroblast growth factor may regulate glioma growth and progression independent of its role in tumor angiogenesis and that basic fibroblast growth factor release or secretion may be required for these actions (Morrison, R. S., et al., J. Neurosci. Res., 34:502-9 (1993)).
Fibroblast growth factors, such as basic FGF, have further been implicated in the growth of Kaposi's sarcoma cells in vitro (Huang, Y. Q., et al., J. Clin. Invest., 91:1191-7 (1993)). Also, the cDNA sequence encoding human basic fibroblast growth factor has been cloned downstream of a transcription promoter recognized by the bacteriophage T7 RNA polymerase. Basic fibroblast growth factors so obtained have been shown to have biological activity indistinguishable from human placental fibroblast growth factor in mitogenicity, synthesis of plasminogen activator and angiogenesis assays (Squires, C. H., et al., J. Biol. Chem., 263:16297-302 (1988)).
U.S. Pat. No. 5,155,214 discloses substantially pure mammalian basic fibroblast growth factors and their production. The amino acid sequences of bovine and human basic fibroblast growth factor are disclosed, as well as the DNA sequence encoding the polypeptide of the bovine species.
Newly discovered FGF-9 has around 30% sequence similarity to other members of the FGF family. Two cysteine residues and other consensus sequences in family members were also well conserved in the FGF-9 sequence. FGF-9 was found to have no typical signal sequence in its N terminus like those in acidic and basic FGF. However, FGF-9 was found to be secreted from cells after synthesis despite its lack of a typical signal sequence FGF (Miyamoto, M. et al., Mol. and Cell. Biol., 13(7):4251-4259 (1993). Further, FGF-9 was found to stimulate the cell growth of oligodendrocyte type 2 astrocyte progenitor cells, BALB/c3T3, and PC-12 cells but not that of human umbilical vein endothelial cells (Naruo, K., et al., J. Biol. Chem., 268:2857-2864 (1993).
Basic FGF and acidic FGF are potent modulators of cell proliferation, cell motility, differentiation, and survival and act on cell types from ectoderm, mesoderm and endoderm. These two FGFs, along with KGF and AIGF, were identified by protein purification. However, the other four members were isolated as oncogenes., expression of which was restricted to embryogenesis and certain types of cancers. FGF-9 was demonstrated to be a mitogen against glial cells. Members of the FGF family are reported to have oncogenic potency. FGF-9 has shown transforming potency when transformed into BALB/c3T3 cells (Miyamoto, M., et al., Mol. Cell. Biol., 13(7):4251-4259 (1993).
Androgen induced growth factor (AIGF), also known as FGF-8, was purified from a conditioned medium of mouse mammary carcinoma cells (SC-3) simulated with testosterone. AIGF is a distinctive FGF-like growth factor, having a putative signal peptide and sharing 30-40% homology with known members of the FGF family. Mammalian cells transformed with AIGF shows a remarkable stimulatory effect on the growth of SC-3 cells in the absence of androgen. Therefore, AIGF mediates androgen-induced growth of SC-3 cells, and perhaps other cells, since it is secreted by the tumor cells themselves.